The invention relates to angioscopes and procedures using angioscopes, and particular to an angioscope having on its distal end a transparent balloon having a distal cavity that communicates with a central channel of the angioscope to allow passage of laser fibers, biopsy forceps, or other instrument through the transparent balloon and into the distal cavity.
Fiber optic cardioscopes and angioscopes have been developed to allow visualization of intravascular or intracardiac structures without performing a major surgical procedure such as a thoracotomy to accomplish such visualization. In these devices, an inflatable transparent balloon is attached to the distal end of the cardioscope. After the instrument is inserted into a blood vessel, the balloon is inflated and the instrument is advanced through the vein or artery to the desired location. The inflated balloon serves to displace blood, and when the lumen is occluded or the balloon comes in contact with the endothelium of a vessel or cardiac structure, direct viewing can be accomplished. Originally referred to as cardioscopes, fiber optic cardioscopes have become smaller in diameter and have come to be referred to as angioscopes to reflect their utility in intracardiac and intravascular viewing. More recently, angioscopy has been of use for diagnosis and therapy of systemic, coronary and pulmonary systems. One presently known flexible fiber optic angioscope design, which perhaps is the closest prior art, includes an inflatable end-balloon attached tot he distal end of the fiberoptic angioscope. A hollow inflation channel, a light channel, and a viewing channel communicate with the interior of the balloon. Following insertion of the end balloon into a vessel, the balloon is inflated with air or liquid. The balloon serves to occlude a blood vessel or is abutted against an intracardiac structure or the like, and visualization is accomplished. Another design includes an inflatable balloon positioned near but not at the end of the angioscope and is referred to as a near-end-balloon angioscope. After passage of the near-end-balloon angioscope into a vessel, the balloon is inflated, which retards blood flow. A solution such as saline is flushed through a central channel of the catheter to clear blood from the area to be viewed. A third design of prior angioscopes incorporates no balloon in its basic structure. Instead it is passed through a guiding catheter, which itself may or may not have an inflatable balloon, to the area to be viewed. Saline or other solution is flushed to clear the area to be viewed through the guiding catheter or a hollow channel in the angioscope. As a practical matter, the end-balloon angioscope can be used only in diagnosis to allow accurate viewing of intravascular structures, etc., but does not seem adaptable to therapeutic procedures, because biopsy forceps, laser fibers and the like cannot be physically passed through the balloon wall without damaging the balloon. Although laser energy theoretically could be passed through some transparent balloon materials to accomplish certain intravascular procedures, the likelihood of damaging the balloon is high. The near-end-balloon and angioscope without an inflatable balloon both potentially allow for the passage of a laser fiber, biopsy forceps or other instrument to a desired intravascular site. Both these instruments are, however, designed for extracardiac intravascular viewing and have relatively no potential use in intracardiac viewing of lasing, biopsy forcep procedures or the like due to their inability to adequately displace blood from the desired viewing site.
Thus, there remains an unmet need for an improved angioscope structure and method that permit both intracardiac and intravascular visualization, and which also permits accurate lasing, biopsy, or other mechanical procedures to be accomplished on the viewed surface.